Place value subtraction: Subtracting numbers by working with hundreds, tens, and ones separately, starting from the ones place.
- Line up numbers by place value
- Subtract ones first, then tens, then hundreds
- No borrowing needed when top digit ≥ bottom digit in each place
347
- 123
-----
7 - 3 = 4
4 - 2 = 2
3 - 1 = 2
347 - 123 = 224
• Place value alignment: Match digits by position
• Right-to-left subtraction: Start with ones, then tens, then hundreds
• No borrowing needed: When top digit ≥ bottom digit in each place
Borrowing: Taking 1 from a higher place value when the top digit is smaller than the bottom digit.
Ones: 3 < 7 → Need to borrow from tens place
3 < 7, so we need to borrow from tens
Take 1 ten from 5 tens: 5 - 1 = 4 tens
Add 10 ones to 3 ones: 3 + 10 = 13 ones
13 - 7 = 6
4 - 2 = 2
2 - 1 = 1
253 - 127 = 126
• Borrowing rule: When top digit < bottom digit, borrow 1 from next higher place
• Regrouping: 1 ten = 10 ones, 1 hundred = 10 tens
• Adjustment: Reduce borrowed place by 1, increase receiving place by 10
Multiple borrowing: When multiple place values require borrowing due to insufficient values.
Ones: 5 < 8 → Need to borrow from tens
Tens: 0 < 7 → Need to borrow from hundreds first
5 < 8, so we need to borrow from tens
0 < 7, so we need to borrow from hundreds first
Take 1 hundred from 4 hundreds: 4 - 1 = 3 hundreds
Add 10 tens to 0 tens: 0 + 10 = 10 tens
Take 1 ten from 10 tens: 10 - 1 = 9 tens
Add 10 ones to 5 ones: 5 + 10 = 15 ones
Hundreds: 3 - 1 = 2
Tens: 9 - 7 = 2
Ones: 15 - 8 = 7
405 - 178 = 227
• Chain borrowing: When lower place needs borrowing but higher place has 0
• Sequential borrowing: Borrow from higher place first, then work down
• Multiple adjustments: Each borrowing affects the place values accordingly
Subtraction with zeros: When the minuend has zeros in tens or ones place, borrowing requires special attention.
Ones: 0 < 7 → Need to borrow from tens
Tens: 0 < 3 → Need to borrow from hundreds
0 < 7, need to borrow from tens
0 < 3, need to borrow from hundreds first
5 hundreds → 4 hundreds, 0 tens → 10 tens
10 tens → 9 tens, 0 ones → 10 ones
4 - 2 = 2 hundreds
9 - 3 = 6 tens
10 - 7 = 3 ones
500 - 237 = 263
• Zero handling: Zeros require borrowing from higher place values
• Sequential borrowing: Work from highest place down when multiple borrows needed
• Regrouping: Maintain place value structure after borrowing
Comparison after subtraction: Calculating both differences and comparing the results.
Ones: 3 < 7 → Borrow: 13 - 7 = 6
Tens: 1 < 8 (after borrowing) → Borrow: 11 - 8 = 3
Hundreds: 5 - 2 = 3
Result: 336
Ones: 4 < 6 → Borrow: 14 - 6 = 8
Tens: 0 < 9 (after borrowing) → Borrow: 10 - 9 = 1
Hundreds: 4 - 1 = 3
Result: 318
336 > 318
623 - 287 = 336 is greater than 514 - 196 = 318
• Separate calculations: Solve each subtraction independently
• Comparison: Compare final results using place value
• Verification: Check each subtraction for accuracy
Word problem subtraction: Identifying minuend and subtrahend from context and solving using place value subtraction.
Minuend: 425 (total stickers)
Subtrahend: 189 (stickers given away)
"How many left" indicates subtraction: 425 - 189
5 < 9 → Need to borrow from tens
1 < 8 (after borrowing) → Need to borrow from hundreds
4 hundreds → 3 hundreds, 2 tens → 12 tens
12 tens → 11 tens, 5 ones → 15 ones
3 - 1 = 2 hundreds
11 - 8 = 3 tens
15 - 9 = 6 ones
Sarah has 236 stickers left.
• Word problem identification: Determine minuend and subtrahend
• Contextual meaning: Connect mathematical result to real-world situation
• Multi-step borrowing: Handle sequential borrowing when needed
Subtraction verification: Adding the difference to the subtrahend should equal the minuend.
563 - 247 = 316
(Ones: 3 < 7 → Borrow: 13-7=6, Tens: 5-4=1, Hundreds: 5-2=3)
316 + 247
Ones: 6 + 7 = 13 → Write 3, carry 1
Tens: 1 + 4 + 1 = 6
Hundreds: 3 + 2 = 5
Result: 563 ✓
Since 316 + 247 = 563, our subtraction was correct
The subtraction 563 - 247 = 316 is correct.
• Verification method: Difference + Subtrahend = Minuend
• Reverse operation: Addition undoes subtraction
• Accuracy check: Always verify important calculations
Mixed operations: Performing subtraction and addition from left to right following order of operations.
456 - 123
Ones: 6 - 3 = 3
Tens: 5 - 2 = 3
Hundreds: 4 - 1 = 3
Result: 333
333 + 78
Ones: 3 + 8 = 11 → Write 1, carry 1
Tens: 3 + 7 + 1 = 11 → Write 1, carry 1
Hundreds: 3 + 0 + 1 = 4
Result: 411
456 - 123 + 78 = 411
456 - 123 + 78 = 411
• Order of operations: Left to right for same precedence operations
• Sequential calculation: Complete one operation before moving to next
• Carry/borrow handling: Apply place value rules for each operation
Missing number problems: Using inverse operations to find unknown values in subtraction equations.
634 - ? = 287
This means ? = 634 - 287
634 - ? = 287
To find ?, subtract 287 from 634: 634 - 287
4 < 7 → Need to borrow from tens
2 < 8 (after borrowing) → Need to borrow from hundreds
6 hundreds → 5 hundreds, 3 tens → 13 tens
13 tens → 12 tens, 4 ones → 14 ones
5 - 2 = 3 hundreds
12 - 8 = 4 tens
14 - 7 = 7 ones
The number is 347.
• Inverse operations: To find subtrahend, subtract difference from minuend
• Equation setup: Translate word problem to mathematical equation
• Verification: Check: 634 - 347 = 287
Number patterns: Identifying the rule by finding the difference between consecutive numbers.
500 - 450 = 50
450 - 400 = 50
400 - 350 = 50
The pattern is subtracting 50 each time
350 - 50 = 300
300 - 50 = 250
Each subtraction follows the same rule: subtract 50
The next two numbers are 300 and 250.
• Pattern recognition: Find the difference between consecutive terms
• Consistent subtraction: Apply the same operation repeatedly
• Verification: Check that the pattern continues consistently
Minuend: The number being subtracted from
Subtrahend: The number being subtracted
Difference: The result of subtraction
Borrowing: Taking 1 from a higher place value when needed
Regrouping: Changing the form of a number for easier calculation
- Align numbers: Match digits by place value
- Check each place: See if top digit ≥ bottom digit
- Borrow if needed: When top digit < bottom digit
- Subtract systematically: Right to left (ones, tens, hundreds)
• Alignment rule: Match digits by place value columns
• Borrowing rule: When top digit < bottom digit, borrow 1 from next higher place
• Regrouping rule: 1 hundred = 10 tens, 1 ten = 10 ones
• Direction rule: Subtract from right to left (ones, tens, hundreds)
• Verification rule: Difference + Subtrahend = Minuend